The present invention relates to a shock absorber for the suspension system of a motor vehicle.
Known shock absorbers comprise a tube; a piston sealably slidably mounted in the tube and attached to a piston rod, the piston separating a compression chamber from a rebound chamber within the tube; a compression stroke valve mounted on the piston; and a rebound stroke valve mounted on the piston. The compression stroke valve acts as a one way valve to allow flow of fluid from the compression chamber to the rebound chamber through one or more compression flow passages in the piston during the compression stroke of the shock absorber. The rebound stroke valve acts as a one way valve which allows flow of fluid from the rebound chamber to the compression chamber through one or more rebound flow passages in the piston during the rebound stroke of the shock absorber. Typically, the valves comprise a number of discs which cover the flow passages during low speed strokes and which deflect to allow fluid flow during strokes above predetermined speeds. An annular stop member is used to prevent excessive deflection of the compression valve discs. One or more pins associated with the stop member pass through aligned apertures in the deflectable discs and into a corresponding aperture in the piston to provide correct orientation for the discs relative to the piston. The pins are either separately formed, which can create assembly problems, or are stamped out of the stop member, which can create manufacturing and tolerance problems.
It is an object of the present invention to provide a shock absorber which overcomes the above mentioned problems.
The present invention is particularly for a shock absorber having a single tube (sometimes referred to as a monotube damper). The present invention may, however, be adapted for use in a shock absorber having an inner tube and an outer tube (sometimes referred to as a twin-tube damper).
A shock absorber in accordance with the present invention comprises a tube substantially closed at both ends and containing fluid; a piston slidably mounted in the tube and making a sealing fit therewith, the piston separating a compression chamber and a rebound chamber within the tube; a piston rod attached to the piston, having a longitudinal axis, and extending through the rebound chamber and out of one end of the tube; a compression stoke valve comprising one or more deflectable discs mounted on the piston on the rebound chamber side thereof; a rebound stroke valve comprising one or more deflectable discs mounted on the piston on the compression chamber side thereof; a compression flow passage extending through the piston in a direction substantially parallel to the longitudinal axis of the piston rod, opening at one end into the compression chamber, and having an opening at the other end into the rebound chamber which is closable by the deflectable disc or discs of the compression stroke valve; and a rebound flow passage extending through the piston in a direction substantially parallel to the longitudinal axis of the piston rod, opening at one end into the rebound chamber, and having an opening at the other end into the compression chamber which is closable by the deflectable disc or discs of the rebound stroke valve; wherein the deflectable discs of the compression stroke valve have fluid flow apertures aligned with the rebound flow passage; and wherein the compression stroke valve further comprises an annular stop member; and an annular orientation disc positioned between the stop member and the deflectable discs on the side of the deflectable discs remote from the piston; the stop member and the orientation disc having fluid flow apertures aligned with the fluid flow apertures in the deflectable discs; the orientation disc having a pin folded therefrom and extending in a direction substantially parallel to the longitudinal axis, the pin extending through corresponding apertures formed in the deflectable discs into a corresponding slot formed in the piston; and alignment means formed on the orientation disc and the stop member for aligning the orientation disc relative to the stop member.
The present invention provides an arrangement in which the parts of the compression stroke valve can be easily and quickly aligned without tolerance or assembly problems.